# Wbit 3110 summer 2015 unit 3 hw b 6 corresponding to

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WBIT 3110, Summer 2015, Unit 3 HW B 6. Corresponding to Problem and Exercise 9 on page 288. Consider the E-R diagram in Figure 8-24, on page 289 of the text. For the E-R diagram provided in Figure 8-24, rather than draw in the cardinalities, list each relationship and describe its cardinalities . Describe any assumptions you must make about relevant business rules. Are there any changes or additions you would make to this diagram to make it better? Why or why not? This question is worth 20% of the assignment. Each relation, and it’s cardinality (both directions) is worth 4%. You MUST provide a cardinality in EACH direction of EACH relation. Relation Cardinality (MUST) be described in BOTH directions CUSTOMER A one or more (mandatory) cardinality to a zero going from CUSTOMER(one or more/many) to ORDER (zero). A zero on the relationship line of CUSTOMER and ORDER describes minimum cardinality that an order doesn’t have to be places but that a customer could place an order at any time. Meaning customers don’t have to have an order, but could have many. ORDER ORDER generates BACKORDER, ORDER to BACKORDER has a zero to zero relationship, because an order may not generate any backorder, or any backorder may not be generated. ORDERS includes PRODUCTS in a MANY to MANY relationship. PRODUCT PRODUCT is comprised_of COMPONENT in a many to many relationship. BACKORDER BACKORDER has a zero to zero relationship with ORDER COMPONENT COMPONENT are supplied_by VENDOR in a many to many relationship VENDOR VENDOR has a many to many relationship with COMPONENT Assumptions: 1- There could be various customers who can place as many orders as they like, but only one order at a time. An order is placed by only one customer. 2- An order may contain a number of products and a type of product may be included by many orders. 3- An order may generate only 1 backorder. 4- It’s possible that a product is comprised of many components and it may be possible that these components may be used on other products. 5- A vendor may supply various components and a component is supplied by various vendors. Changes or Additions to the diagram: 1- A vendor could also supply finished products. So in the diagram we would add a link between vendor and product with a many to many relationship. See below diagram.
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WBIT 3110, Summer 2015, Unit 3 HW B 12 %age POINT BONUS QUESTION Corresponding to Problem and Exercise 15 on page 288.